NOAA 2001-024
Contact: Delores Clark


Over the northern Pacific Ocean, beyond the reach of land-based weather instruments, a NOAA surveillance jet aircraft is collecting critical meteorological data for operations that meteorologists believe will improve forecasts for storms approaching the West Coast. The Winter Storm Surveillance Program aims to improve the National Weather Service's forecasts for storms affecting the western U.S., and the rest of the nation.

Like the surveillance flights that fly around hurricanes in the Atlantic Ocean, the NOAA G-IV aircraft is measuring the wind speed, temperature and moisture from storms in the Pacific Ocean. The data, retrieved by dropsondes, are sent in real-time to the National Weather Service supercomputer in Bowie, Md. From there, the data are fed into current numerical weather, climate, hydrologic and ocean forecast models.

"Research results have shown that when meteorologists have this type of data sooner, it gives them a definite advantage for predicting winter storms in the short-and medium-term," said Louis Uccellini, Ph.D., director of the National Centers for Environmental Prediction.

The Winter Storm Surveillance Program began as an experiment during the peak of the 1997-98 El Niño, when a parade of storms battered the West Coast. In some instances, researchers discovered a 60 percent increase in the accuracy of computer model guidance, the basis for the NWS's weather forecasts, for some of the storms, and improvements of 10 and 20 percent in medium- and short-range weather models, respectively.

This year, the program evolved from a research mode and became fully operational. The G-IV started its flights out of Honolulu on Jan. 15, and will end Feb. 20.

The Environmental Modeling Center, along with other participating scientists, developed a strategy to target specific areas in the atmosphere where they are most needed. Zoltan Toth, Ph.D., the program's lead scientist, said, "This strategy makes use of an array, or an ‘ensemble' of forecasts, which indicate where data are most needed for improving the forecasts."

Naomi Surgi, Ph.D., the EMC's advanced project leader said, "As with any system in nature, if you want to be able to predict winter storms over the next four to five days, you have to be able to describe, with as much accuracy as possible, what that system is doing now -- especially over the Pacific Ocean."

While NOAA has an extensive network of Doppler weather radars, weather balloons, advanced satellites and surface observing systems across the United States, atmospheric data over the Pacific Ocean is sparse. The surveillance program has allowed the NWS to analyze pertinent atmospheric data that has never been obtained before.

"Basic winter weather patterns normally move from west to east. Gathering atmospheric data over the Pacific Ocean helps NWS scientists to capture weather patterns where they form," Toth said.

"It is remarkable that through five years of research and development, we can now determine where and when observations should be made to improve forecasts," said Stephen Lord, Ph.D., EMC director. "This work enables NOAA scientists to make the most effective use of the nation's observing resources for improving weather forecasts for severe winter weather events, and mitigate the impact of dangerous storms."

"The G-IV is NOAA's newest reconnaissance aircraft and is particularly suited for these flights because of its speed and range," said Jack Parrish, flight meteorologist and G-IV program director at NOAA's Aircraft Operations Center in Tampa, Fla. "The G-IV is a high-altitude, high-speed, twin-turbofan jet that flies at altitudes up to 45,000 feet. During this project it is flying more than five million square nautical miles around the jet-stream level, as well as through its center, where winds may reach as high as 200 mph."

The G-IV is primarily used in surveillance flights during the hurricane season to gather data needed to forecast the track of a hurricane. At the conclusion of the program, the G-IV will return to Florida to gear up for the upcoming hurricane season.

The Environmental Modeling Center, one of nine National Centers for Environmental Prediction, develops and improves numerical weather, climatic, hydrological and oceanic predictions through programs of applied research in data analysis, modeling and product development in partnership with the broader research community.

NOTE TO EDITORS: Media are invited to ride aboard the G-IV on a space-available basis. Please contact Delores Clark at the National Weather Service in Honolulu,
(808) 532-6411, to arrange a ride.